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| 0.2.0 | Dec 22, 2021 |
| 0.1.0 | Dec 18, 2021 |
#2237 in Rust patterns
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Building an inductive trait on all tuples (up to length 32).
First you will need to provide all tuples with a marker. This is done with
mark_tuples!(MyMarker)
Then you define a trait that you want to apply to aa tuples of up to length 32:
trait MyInductiveTrait {
type AccumulatedTupleType;
fn fn_to_build_accumulated_type_from_self(self) -> Self::AccumulatedTupleType;
}
Then define the trait for the one-tuple (i.e. the start of induction)
impl<A> MyInductiveTrait for (A,) {
type AccumulatedTupleType = (MyStruct<A>,);
fn fn_to_build_accumulated_type_from_self(self) -> Self::AccumulatedTupleType {
let (a,) = self;
(MyStruct::new(a),)
}
}
The hardest is the induction step, where you will probably need a good many trait bounds:
impl<TupleType, Head, PrevTupleType, PrevAccumulatedTuple> MyInductiveTrait for TupleType
where
TupleType: PreviousTuple<Head = Head, TailTuple = PrevTuple> + MyMarker,
// You need the `MyMarker` trait because otherwise the compiler complains about potential
// changes to the PreviousTuple implementation.
PrevTuple: MyInductiveTrait<AccumulatedTupleType = PrevAccumulatedTuple>,
PrevAccumulatedTuple: NestTuple,
(PrevAccumulatedTuple::Nested, MyStruct<Head>): UnnestTuple
{
...
}